Stirring molten glass in continuous tank furnaces



Nov. 26, 1935. w. c. TAYLOR 2,022,223

STIRRING MOLTEN GLASS IN CONTINUOUS TANK FURNACES Filed May 13, 1952 2 Sheets-Sheet l IN V EN TOR.

A TTORNEYS.

NOV. 26, 1935. w c TAYLOR 2,022,223

STIRRING MOLTEN GLASS IN CONTINUOUS TANK FURNACES Filed May 15, 1952 2 Sheets-Sheet 2 VENTO'R. um/v m YLOR A TTORNEYS.

Patented Nov. 26 1935 UNITED STATES PATENT-OFFICE 7 V 2 2,022,223

STIRRING MOLTEN GLASS 1N CONTINUOUS TANK FURNACES poration of New York Application May 13, 1932, Serial No. 611,204

3 Claims.

This invention relates to a device for stirring the molten glass in a continuous tank furnace.

In order to obtain the highest possible degree of homogeneity in glass which is melted in pots and particularly in optical glass it has been customary to stir the molten glass with a clay stirring rod suspended vertically in the glass and rotated about a vertical axis. ring when applied to a continuous tank furnace for obtaining homogeneous glass because when such a stirrer is used in the melting end of a tank some of the unmelted or faulty glass is carried by its action toward the delivery end of the tank faster than would be the case if no stirrer were used.

It has been proposed to stir molten glass in continuous tank furnaces by means of a clay stirring rod having a straight reciprocating motion transversely of the tank. It is known that the flow of molten glass from the melting end towards the delivery end of the tank is more rapid at the surface and although this type of stirrer does not tend to sweep faulty glass toward the delivery end of the tank it does not afford suflicient mixing of the non-homogeneous top and bottom layers.

The object of the present invention is to stir molten glass in a continuous tank furnace so as to produce homogeneous glass at the delivery end of the tank.

The above object may be attained by practicing my invention which embodies among its features astirring rod rotated about a substantially horizontal axis. The stirring rod preferably is offset near the stirring end to enhance the stirring action and the depth of the offset is dependent upon the degree of stirring action desired and upon the angle to which the stirring rod is inclined. The rod is rotated in a direction which is counter to the surface flow of the glass thus carrying back the surface portion of the molten glass' and forcing it down to be mixed with the 55 tion;

This method of stirpossesses no advantage and in fact is detrimental Fig. 1, showing my stirring device in side eleva- Fig. 3 is a side view partly in section of a clay stirring thimble made in accordance with my invention.

Fig. 4 is a plan view of the melting end of a tank showing a modification of my invention. 5

In the drawings, a tank designated generally I0 is provided with stirring rods ll placed in a substantially horizontal position and adapted to be rotated about their longitudinal axes. The driving means are preferably individual units, synchronized or not as desired, attached to each rod but only one is shown in the drawings (Fig. 2). This comprises a pulley l2 driven by a belt l3 passing over an idle pulley H to a motor 15. Each stirring rod is supported by a set of four 16 rollers, two of which are shown at I8 and are attached to the side of the tank "I by a supporting bracket H. The outer end of the stirring rod H is supported by a bearing l8 and the rod is prevented from shifting endwise by two ad- 2 justable collars l9. On the end of the stirring rod which is immersed in the molten glass is a clay thimble or stirring finger 20 which is of suflicient length to project somewhat above the- Iii level of the glass. Cooling of the rod is accom- 25' plished by means of water admitted from a source not shown through an inner tube 2| which extends through the rod II to the closed end thereof (Fig. 3), at which point the water emerges from the tube 2| and returns through the rod II to a swivel joint 22where it is carried away by a waste line 23. The clay thimble 20is preferably provided with a bend or offset 24 located about midway of its length as shown in Figs. 2, 3, and 4.

It will be observed from a contemplation of Fig. 2 that my stirring rod has a retrograde stirring action in that it moves counter to the surface flow of the glass and hencecarries the surface glass back down to be with the more stagnant under layers thereof. It thus tends not 40 only to prevent segregation into layers but also to hold the unmelted batch for a longer time near the melting end of the tank and 'thus produce better homogeneity in the glass when it finally 5 approaches the delivery end of the tank. It will be obvious that the stirring action of my device can be increased or decreased by increasing or decreasing the depth of the bend in the clay thimble or by increasing or decreasing the length of the'thimble.

In Fig. 4 I have shown an alternative arrangement of my device wherein the twostirring rods are not placed opposite to each other as in Fig. 2

but are spaced somewhat apart so as to a Elsi; as

thestirringrodstoextendacromtotherespective further sides of the tank. This has the added advantage that the stirring rods can be lowered to a more nearly horizontal position and affords a decided increase in the stirring action with a relatively slight bend in the thimble.

Although in the, foregoing there has been shown and described the preferred embodiment of my invention, is to be understood that minor changes in the details of construction, combination and arrangement of parts may be resorted to without departing from the spirit and scope of the invention as claimed.

- What I claim is:

1. The combination with a continuous tank Iumace formelting glass, of a stirring rod mounted intermediate the ends of themelting chamber of the furnace for rotation a substantially horizontalaids and a bent stirring thimble on the end of the rod for contact with the glass.

7 2. The combination with a continuous tank furnace for melting glass, of stirring rods mounted intermediate the ends of the melting chamber I 3. The combination with a continuous tank 10 furnace for melting glass, of stirring rods mounted intermediate the ends of the melting chamber of the tank and spaced alternately through the sides thereof, said rods being rotatable about substantially horizontal axes and a bent stirring l5 thimbld on each of said rods for contact with the glass.

WILLIAM C. TAYLOR. 

